Electrical substation



Jan. 1,1935. D. K. BLAKE I ELECTRICAL SUBSTATION Original Filed Maxch l6, 1931 Inventor: David K. BlaKe, b9 11 660 His AtLor-neg.

Patented Jan. 1, 1935 UNITED STATES PATENT OFFICE ELECTRICAL SUBSTATION David K. Blake, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Original application March 16, 1931, Serial No. 523,140. Divided and this application February 7, 1933, Serial No. 655,601

Claims. (Cl. 175298) My invention relates to apparatus of electrical mitted to relatively large substations from which distribution systems and particularly to an electhe energy is distributed at a medium voltage trical substation for alternating current network by radially extending feeders. Each of these systems of distribution, feeders supplies a separate load area through the 5 This application is a division of my applicausual distribution transformers which step the 5 tiOn Serial No. 523,140, filed March 16, 1931 and voltage down to the standardized low voltage. assigned to the assignee of the present applioa- The low voltage circuits may or may not be intertion, connected to form a low voltage network. Usu- It is a matter of common knowledge that the ally in hi h loa d nsity load areas such a netvoltage of the electrical energy which operates Work a most easily be formed and it is in such 10 the lights, radio sets, toasters, fans and all the areas that the advantages of Continuity of s numerous other appliances hi h play such ice which results in the interconnection is most large part in the daily life of most persons is desirablepractically standardized throughout the country. The radial System has y disadvantages,

It is this standardization which in turn permits most all Of Which can be attributed to e a e 15 the standardization of th various appliances custom made substations. Thus the large conwith the result that th full benefits of 1 indicentrations of power necessitate elaborate and vidual cost mass production can be realized. This expensive Protective equipment The n sa y standard voltage is relatively low, it usually beunequal lengths of the feeders equ re ind vidual ing very close to 115 volts. One reason that the Voltage regulators n each feeder. The nature of 20 st d d voltage is relatively 1 is t t t the system requires diflicult and expensive long danger of accidental injury or electrocution is range load forecasting, the difficulty d expense mu h l t l voltage th t, high voltage of obtaining satisfactory sites for substations,

It is also a well known fact that up to certain usually resulting in Compromise locations, and

maximum values it becomes more economical to the growing Pressure of publ c Opinion requiring 25 t it d distribute electrical energy the highexpensive landscaping and architectural beautier the transmission or distribution voltage. This ficatioh 0f the Substation SiteS- Furthermore, i because a given amount of eieetrieai power at the engineering design of each substation pre- Ieiativeiy high voltage represents a [relatively sents individual problems and difiiculties dependsmall current flow and consequently a relatively mg upon the nature of Its location, the a tiei- 30 small resistance loss in the conductors of the cirh e q growth and many other ac rs- A given amount f power can the efo e he Tne radial system has the added disadvantage transmitted with iess copper at high voltage that it requires a relatively large amount of copt at 1 voltage f r the same less, per in that many of the radial feeders are neces- The problem in electrical distribution is there- Barfly parallel to each other for o ions o their 35 fore to provide a system which will best and most length: reliably and economically distribute electrical endlshhghlshed the radlal System y inergy throughout large load areas, such as towns ventlon has to do with a medium voltage system d cities and their Suburbs and which at the network of distribution involving one or more of Same time will make the energy avaiiahie at a my novel standardized unit substations which are 40 standard 10W veitage connected in the network at points where the lead A furth r factor which complicates the density is less than a predetermined amount, said ter is the fact that in any large load area the load medium Voltage network serving to supply the density varies greatly from the very high density 10W 10945 density P01110113 Of a low voltage netdowntown business sections to the low density q Whose e' load density i ns are sup- 45 Outlying residential sections. plied directly through transformers from high Still th difficulty lt from t fa t voltage transmission circuits, said substations bethat the load density of various sections is cons Capable of removal as units as t mad dentinually changing. Thus the load density is ususity of the eas they serve exceed a p t ally growing radially Outward as th city or t mined amount and being capable of reinsertion in 50 expands. said network at points where the load density In the past the usual distribution system has has not yet reached said predetermined value. been what may conveniently be called the radial The above system, however, is not limited to system. In this system the generated electrical cases where the low voltage distribution conducenergy is stepped up to high voltage and transtors are interconnected to form a network at 55 down transformer 7.

times when the load density is less than a predetermined value and it includes cases where these conductors are not so interconnected at these times, they being only interconnected to form a low voltage network at the time they are to be fed directly from the high voltage feeder circuits through step down power transformers instead of from the unit substations through the medium voltage network.

An object of my invention is to provide a novel standardized unit substation for use in my system of distribution.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawing Fig. 1 is a diagrammatic showing of the main circuits of the standardized unit substation embodying my invention, Figs. 2, 3 and 4 are respectively elevation, plan and end views of my unit substation.

In Fig. 1. wherein is illustrated diagrammatically the main circuitsof my substation, together with the main electrical elements thereof, 5 is a three-phase high voltage transmission circuit which upon entering the substation is connected to the primary winding of a three-phase step- Although it is obviously not necessary, I prefer to employ an auto-transformer, asshown, because such a transformer has about 25 per cent lower losses than theordinary transformer, while it also has considerably smaller physical dimensions for equal power rating.

The particular voltage regulating means which I prefer to employ, isthe transformer tap-changing type or load ratio control type voltage regulating means illustrated diagrammatically at 8 in the drawing. This tap-changing means may be points of the transformer as shown so that it may be connected to the fourth or ground wire of the feeder circuit. In order to suppress harmonics which are likely to cause telephone interference, I preferably provide the transformer with a delta connected winding 9. g

For preventing a reverse power flow thro th transformer from the network in case of a fault on the transmission circuit 5, I provide a transformer circuit breaker 10. Connected to this circuit breaker 10 is a substation bus 11 to which are connected four medium voltage network circuit breakers 12, whose function it is to sectionalize that portion of the network on which a fault occurs.

The individual substations, which are in themselves standardized units, are made up of standardized component elements. The result is that these units may be manufactured on a production basis which will greatly reduce their cost per k. v. a. These unit substations are preferably made small enough so that they may be factory assembled and shipped direct on flat cars as units to the place where they are to be installed. A specific example of such a unit would be a unit of about 1500 k. v. a. capacity, which, when assembled, would be about 2'? feet long by 5 feet wide by about 8 feet high, the entire unit weighing less than 25 tons. Such a unit would readily fit into avault built beneath the surface of a street. Furthermoresuch a vault need not be more than about 8 or 9 feet wide, so that its construction necessitates tearing up but half of the street and consequently the entire street need not be blocked to traffic while one of these units is being installed.

Referring now to Figs. 2, 3, and 4 which illustrate views of a physical embodiment of a preferred form of standard unit substation which is enclosed in a concrete vault 13. As shown, this vault is provided with end ventilating compartments 1% and 15, which are open to the atmosphere through gratings l6 and 17. Suitable drains l8 and 19 are provided for removing rainwater, etc. Blowers or fans 20 are provided for securing the necessary ventilating air flow through the vault.

The arrangement of the main electrical elements is such that the incoming power through transmission circuit 5 enters transformer '7, passes therethrough and to circuit breaker 10 from which it flows through the enclosed substation bus 11 to the feeder circuit breakers 12. The main elements are thus arranged in a straight-line in the order of power flow therethrough. The load ratio control voltage regulating means for the transformer is enclosed in an end-housing 21 on the transformer. The disconnecting and grounding switch for the transformer is located in a housing 22 thereon, while the terminals of the tertiary winding of the transformer are enclosed in a housing 23 on the transformer. Bus 111 is enclosed in a metal casing 24 which is filled with an insulating compound thereby rendering the bus virtually short circuit proof. Above this housing are mounted a plurality of small housings 25which enclose the connections of the medium voltage network feeders to the bus and which also enclose the usual current transformers for controlling the relays which trip the circuit breakers, All of the relays and recording instruments of the substation are mounted in a substantially constructed metal compartment 26. This has the advantage of centralizingall of this equipment in a waterproof compartment which is at the low voltage end of the substation. Through this arrangement the parts which will need most constant inspection are all mounted as remotely as possible from the high voltage transformer end of the substation.

For gaining access to the vault enclosing the substation I provide a door, which inthe illusthe substation will enter it at its low voltage end 1 1 and nearest to those elements which will require most frequent inspection.

N0 medium voltage network disconnecting devices independent of the oil circuit breakers 12 are employed. These circuit breakers which are of the well known metal clad type are so arranged connection with the bus 11 that they may be connected or disconnected thereto by raising or lowering through the use of the conventional rod and socket connections. Such a standardized unit substation as ha been described, with all its internal connections completed, greatly simplifies the layout of a distribution system so the substation may be transported directly from a fiat car to the vault. The high voltage input line connected to the transformer and the network feeders connected to the oil circuit breakers, and the substation is practically ready to be put into operation. The tertiary winding on the transformer is preferably used as the oil circuit breakers and also for operating the motors of the blowers 20.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination, a standardized transformer, a. standardized transformer circuit breaker, and a standardized feeder circuit breaker, said standardized devices being physically arranged to form a unit substation whose overall width is substantially equal to the width of the widest of said devices.

2. A standardized unit electrical distribution substation having, in combination, an elongated enclosure, high voltage apparatus at one end of said enclosure, low voltage apparatus at the other end thereof, and a normally closed entrance in said closure adjacent said low voltage apparatus and remote from said high voltage apparatus.

3. An enclosed standardized unit electrical distribution substation including high voltage apparatus which requires relatively infrequent inspection, low voltage apparatus which requires relatively frequent inspection, and an entrance in the enclosure of said unit adjacent said low voltage apparatus and remote from said high voltage apparatus whereby a person entering said substation will encounter the low voltage apparatus before encountering the high voltage apparatus.

4. In combination, an enclosed unit substation including in sequential arrangement a high voltage intake circuit, a step down transformer, oil circuit breakers, a compartment for housing the protective relays and instruments of the station, and a normally covered entrance in the enclosure of said unit for allowing access thereto for inspection and repair, said entrance being adjacent said relay and instrument compartment whereby an attendant entering said compartment through said entrance enters at the low voltage end of said station.

5. A standardized medium voltage network electrical distribution substation including, in combination, a standardized voltage step-down power transformer, a standardized feeder circuit breaker, a standardized network circuit breaker, said devices being arranged in a row in the order of power flow through said station and with the lengths of said devices substantially in a line so that the width of said station is substantially the width of the widest of said devices.

DAVID K. BLAKE. 

